SOFIA, Oct 30 (Reuters) - Bulgarian Prime Minister Boiko Borisov claimed victory on Sunday for his party’s candidate, Rosen Plevneliev in a presidential run-off with 54 percent support which would tighten his grip on power before a 2013 parliamentary election.

Alpha Research and Gallup International polls put Plevneliev ahead of Socialist Ivailo Kalfin, with the margin indicating the Socialists are recovering from a crushing defeat in 2009 and will most likely be the main challenger for the ruling GERB party in the next vote.

“We will take the confidence (we received) very responsibly so that in two years’ time to achieve the same results,” Borisov told a news conference.

After hearing the results earlier in the evening, visibly excited, the newly-elected president shook hands and hugged supporters amid victory chants in GEBR’s election headquarters.

“From now on you can expect our claim for modern governance and for speeding up Bulgaria’s European development,” Plevneliev said after Borisov gave the floor “to the new president”.

Plevneliev’s winning the highly ceremonial presidential role would remove the possibility of government-initiated legislation or appointments being vetoed by Socialist President Georgi Parvanov who has often criticised the cabinet.

“GERB’s victory means stable governance,” said independent political analyst Rumiana Kolarova. “It is definitely good for Bulgaria, because the cabinet will not be blocked.”

Exit poll results also showed GERB won the mayoral posts in major cities such as the Black Sea city of Varna, the central city of Stara Zagora and the Danube town of Rousse among others.

Analysts say Borisov is unlikely to risk potentially unpopular overhauls of healthcare and pensions but will keep tight fiscal discipline to protect Bulgaria’s financial stability and will carry on with large-scale infrastructure improvement.

He will also be keen to demonstrate Bulgaria’s progress by ensuring it joins the EU’s passport-free Schengen zone, from which it has been blocked due to corruption concerns, before the 2013 election.

GRAFT FIGHT

The campaign was blighted by rallies against the Roma minority and corruption highlighting the cabinet’s struggle to address unemployment, graft and the fragile position of ethnic minorities.

Former construction minister Plevneliev, 47, has pledged to step up efforts to fight corruption in the public sector and to work towards the approval of the bill authorising widespread confiscation of illegally obtained assets.

Previously manager of a major building company, he has also announced plans to set up councils to monitor economic policy, as well as the much-needed structural reforms.

“Plevneliev has a clear idea of what to do and how to do it,” said teacher Yanka Georgieva, 49. “He’s a successful businessman, a successful politician and it’s time to be a successful president.”

Turnout was about 40 percent at 1500 GMT, organisers said, and official results from the second round in the presidential race and the local elections held on Sunday are expected on Monday.